diff --git a/src/wormhole/cli/cmd_send.py b/src/wormhole/cli/cmd_send.py
index 24d9b1c..958f794 100644
--- a/src/wormhole/cli/cmd_send.py
+++ b/src/wormhole/cli/cmd_send.py
@@ -85,7 +85,7 @@ class Sender:
         if not args.zeromode:
             print(u"Wormhole code is: %s" % code, file=args.stdout)
             # flush stdout so the code is displayed immediately
-            sys.stdout.flush()
+            args.stdout.flush()
         print(u"", file=args.stdout)
 
         yield w.establish_key()